Recovery of sulfonic acids from petroleum fractions



July 31, 1956 J. F. HUTTO ET AL RECOVERY OF SULF'ONIC ACIDS FROM PETROLEUM FRACTIONS Filed Jan. 2, 1952 ATTORNEYS United States RECOVERY F 'SULFNIC ACIDS FROM PETRLEUM FRACTIONS Application January 2, 1952, Serial No. 264,436

Claims. (Cl. 26h- 504) This invention relates to sulfonic acids. more specific aspects, this invention relates to the recovery of water insoluble sulfonic acids. ln another of its more specific aspects, it relates tothe recovery of sulfonic acids as a by-product of a process for oxidation of petroleum stocks with S03 or sulfuric acid. ln another of its more speciiic aspects, this invention relates to the separation of sulfonic acids and an oilV phase containing products of oxidation produced in a process for oxidizing petroleum with S03.

A'shless detergents for use in lubricating oils and greases are prepared by the oxidation of petroleum with-S03 as disclosed by W. B. Whitney incopending U. S. application, Serial No. 304,659, ledi August 15, 1952. Such oxidized products must be substantially neutralized before their incorporation. in lubricating oils and greases s-o as to obtain the best possible results therefrom.

lt is known that some sulfonic acids are Water-soluble while others are substantially water-insoluble. The watersolubie sulfonic acids can be substantially removed from the oil phase containing the oxidized material by waterwashing. Additional sulfonic acids can be removed by alcohol washing of the oil phase containing the oxidizedl materials. The oil phase product obtained from this alcohol-'washing step, however, still has an excessive acid content resulting from high molecular weight sulfonic acids which are not soluble in water or alcohol. This has heretofore made it necessary to neutralize the acid with a basic material such as guanidine or another basic material. The neutralization without recovery of these sulfonicv acids in this manner results in a considerable waste of sulfonic acids. We have discovered a method' whereby the acid contentV in the oil phase can bereduced below a critical point so as to make possible the use of the oxidized material and yet` permit the recovery of the sulfonic acidsv per se for use in any manner desired. The recovery of sulfonic acids from the oil phase after treatment of such oil with sulfuric acid presents similar problems and is dealt. with in the same manner as utilized in connection with the recovery of sulfonic acids from the` oil phase obtained by treatment of the oil with S03.

Each object. of this invention is attained by atleast one aspect of this invention.

An. object of this invention is to provide an improved method; for recovery ofsulfonic acids. Another object of' the invention is to provide. a method for the recovery ofsuicientfsulfonic acidsV from' the oilV phase obtained by treatinga petroleumA fractionation with S03 tov permit the recovery and use of' oxidation products without further neutralization'. Another object'of the inventionis' to'provideea method for the recovery of water insolublesulfonic acids resultingfrom the treatment of a petroleum fraction with S03' or H2804: Another object of the invention= is to concentrate high molecular weight sulfonic acids. Other' and? further objects of the invention will be apparent upon studyof the accornlzvanyingl disclosure and' the drawing.Y

vBroadly speaking, this invention resides inthe utiliza- In one of its atent V'ice tion of a mixture of isopropanol and dimethyl formamide as a solvent for the recovery of wa'terdnsoluble and alcohol-insoluble sulfonic acids. The result obtained by means of our invention is completely unexpected since dimethyl formamide when used alone fails to recover any more of the sulfonic acids than is obtained by the utilization of isopropanol alone as the solvent.

Better understanding of this invention will be obtained upon study of the accompanying drawing which constitutes a diagrammatic flow scheme utilized in the process ofV this invention. As pointed out in the Whitney application, identified above, the oil charge stock to the oxidation zone is preferably one which has been purilied so as to remove asphalt and other` similar impurities therefrom. The oil charge stock is introduced int-o a treating chamber 11 through inlet conduit 12 and valve 13. A solution of S03k in ethylene chloride is introduced into the treating zone through conduit 14 and valve 15 which may, as shown in the drawing, be connected to thel oil feed conduit or may be connected separately to the oil treating chamber. During the treatment of the oil within chamber 11, the oil` is oxidized with a concomitant pro# duction of sulfonic acids. An oil phase is rernoved from? chamber 11 through conduit 16 to the lower end portion of water wash chamber 17.

Water is introduced into the upper end portion of chamber 17 through conduit 18 and valve 19 and is passed- 'through wash chamber 17 in direct contact wit-h the oil phase from chamber 11. A- portionof the sulfonicV acids are dissolved in thewater and areA removed from the lower portion of chamber 17 through conduitV 21 and valve 22 together with excess water. The overhead efiiuent from chamber 17 contains the ethylene chloride, oil, oxidized product, and Water-insoluble sulfonic acids. The overhead efliuent from chamber 17 passes by means of conduit 23 to an intermediate portion` of fractionator 24 wherein ethylene chloride is distilled off andi removed through eiuent conduit 25 and valve 26. The oil, ox-idized products, and water-insoluble' sulfonic acids are removed from the lower end portion of fractionat'or 24 and are passed by means of conduit 27 to an intermediate portion of alcohol ertraction chamber 28.

Isopropanol or another alcohol, preferably in the C2 to C5 range, is introduced into the lower portion of extractor 28 through conduit 29 and valve 31. The alcohol passes upwardly through extractor 28 and through thel oil phase, in direct contact therewith. A portion of the water-insoluble sulfonic acids are dissolved inthe alcohol-extraction step and are removedv from the upper endl portion of extractor 2S together with excess alcohol through conduit 32 and valve 33. The oil, oxidized products, and alcoholinsoluble sulfonic acids are removed from the lowerend portion of extractor 28- through conduit 34 andA are passed to anintermediate portion of extraotorSS.

A mixture of alcohol, such as used' in extractor cham'- ber 2S, and dimethyl formamide is used as the solvent in extractor chamber 35. The solvent mixtureis introduced into the lower portion of chamber 3'5' through' conduit 3'6 and valve 37. The solvent is passed upwardly through the oilV phase and' in direct contact therewith. A considerable portion of the alcohol-insoluble sulfonic acids are dissolved in the solvent mixture and are ,removed from the upper end portion of extractor chamber 35 through conduit 38' and valve 39. The oil phase containing oxidation products are removed from the lower end portion of extractor chamber 35 through conduit 41 and valve 42. The oxidation products are thenV separated from the oil in any manner desired and are used without further purification. The sulfonic acids removed by the-water extraction, alcohol extraction and' alcohol-dimethyl formamide extraction are recovered' from the various solvents by means/of distillation and are utilized as desirable products of the reaction.

As pointed out above sulfonic acids are also produced by the treatment of an oil fraction with sulfuric acid. When sulfuric acid is utilized as the treating material, it will not be necessary to use the ethylene chloride in the system. Thus, when sulfuric acid is used as the treating agent in chamber 11, each of the recovery steps described above are utilized with the exception of the fractionation step in chamber 24 which is used only to remove the ethylene chloride.

We have discovered that by the use of a mixture of dimethyl formamide and an alcohol (e. g. ethyl, isopropyl, etc.) we obtain a substantial reduction of the acid content of the product obtained from the treatment of oil with S03 or sulfuric acid. In this process, the S03 or H2504 treated petroleum fraction which has been water washed and alcohol extracted is extracted one or more times with the mixed solvent. The preferred concentration of dimethyl formamide in the mixed solvent is in the range of between 20 per cent and 80 per cent by weight. The extraction of the acids in the mixed solvent step is usually carried out at a temperature below the boiling point of `the solvent at contact conditions, preferably at a temperature Within the range of between 70 F. and 180 F. and more preferably at a temperature within the range of between 120 F. and 130 F. The contact is preferably maintained at atmospheric pressure and for a period of between and 30 minutes. The extraction is usually continued until 95 to 98 per cent of the original titratable 'acidity is removed from the oil phase containing the high molecular Weight petroleum sulfonic acids.

The following example is presented for the purpose of clarification and as an aid in more particulary presenting the invention. This example should not be interpreted as unduly limiting the scope of this invention.

Example 3.21 pounds of S03 were mixed with 5.3 pounds of ethylene chloride while cooling the mixture by external means. This mixture was added to a mixture containing pounds of propane-fractionated, phenol-extracted SAE 250 lubricating oil and 7.95 pounds of ethylene chloride. The mixture was passed to water extraction in six-foot spinning band glass column of 2-inch diameter. The Water-to-oil ratio was held at approximately 1:1 while countercurrent contacting was obtained. Five passes through the column were made, reducing the titratable content of the oil to 1.0 per cent acid expressed as S03. The water-soluble sulfonic acids were removed from the system and the oil mixture was then passed to a distillation column wherein the ethylene chloride was removed. The oil was then batch extracted three times with one volume of isopropanol in each extraction. The iirst extraction reduced the acid in the oil mixture to 0.24 weight per cent expressed as S03. The second alcohol extraction reduced the acid to 0.20 weight per cent expressed as S03. The third extraction removed practically no acid, leaving an acid content of 0.19 per cent expressed as S03 after this extraction.

In an eiort to reduce the acid content in the oil phase still further, a small scale extraction was made using dimethyl formamide as the oil solvent. This extraction failed to reduce the acid content of the oil phase. A full scale extraction of the alcohol-extracted oil was made using a 50-50 mixture of isopropanol-dimethyl formamide. A 1:1 volume ratio of the solvent to oil was heated to 180 F. at atmospheric pressure and was then allowed to cool to a temperature between 120 F. and 130 F. The contact was maintained for about 30 minutes and lowered the acid content from 0.19 weight per cent to 0.11 weight per cent expressed as S03. The critical acid content is about 0.14 weight per cent expressed as S03. It will be seen that by the utilization of our invention the acid content of the oil phase obtained from the treatment of oil with S03 can be reduced to such an extent that further neutralization thereof is unnecessary.

Various modifications of this invention mayl be made in line with the foregoing disclosure. It is believed that such modifications are clearly within the spirit and scope of this invention.

We claim:

1. The process of recovering sulfonic acids from a petroleum fraction containing said acids, which comprises the steps of contacting said petroleum fraction with a solvent mixture of at least one alkanol, selected from the group consisting of C2 to C5 alkanols, and dimethyl formamide, the ratio of said alkanol and dimethyl formamide being in the range of 1:4 to 4:1, at a temperature below the boiling point of the solvent at contact conditions but above 70 F. so as to selectively dissolve said acids in the mixture of alkanol and dimethyl formamide; separating said solvent and acids from said petroleum fraction; and separating said sulfonic acids and said solvent.

2. The process of claim l wherein said alkanol is ethanol.

3. The process of claim 1 wherein said alkanol is a Ca alcohol.

4. The process of claim l wherein said alkanol is a C4 alcohol.

5. The process of claim 1 wherein said alkanol is a C5 alcohol.

6. The process of claim l wherein said solvent-petroleum fraction contacting is carried out at a temperature in the range of between 70 F. and 180 F.

7. The process of claim 6 wherein said solvent-petroleum fraction contact is maintained for a period of between 10 and 30 minutes.

8. A process for removing sulfonic acids from a petroleum fraction containing said acids, which process comprises contacting a liquid phase of said petroleum fraction with a separate liquid phase of a solvent mixture comprising at least one alkanol containing from 2 to 5 carbon atoms per molecule and dimethyl formamide, the weight ratio of said alkanol to dimethyl formamide being in the range 1:4 to 4:1, maintaining said solvent substantially in the liquid phase during said contacting, and separating a liquid phase rich in said solvent mixture from a liquid phase rich in said petroleum fraction.

9. A process for recovering sulfonic acids from a petroleum fraction containing said acids, which process comprises the steps of contacting said petroleum Vfraction with a solvent mixture of isopropanol and dimethyl formamide in which the weight ratio of isopropanol to dimethyl formamide is Within the range 1:4 to 4: 1, at a temperature below the boiling point of said solvent mixture at contacting conditions but above 70 F. so as to selectively dissolve said acids in said solvent mixture, separating said solvent mixture and acids from said petroleum fraction, and separating said sulfonic acids from said solvent mixture.

10. In a process of recovering sulfonic acids from a petroleum fraction containing said acids, which comprises the steps of contacting said petroleum fraction with water so as to selectively dissolve a portion of said sulfonic acids in said water; separating said water and dissolved acids from said petroleum fraction; contacting said petroleum fraction and at least one solvent alcohol so as to dissolve a portion of said sulfonic acids in said alcohol; separating said alcohol and dissolved acids from said petroleum fraction; the improvement which comprises contacting said petroleum fraction and a solvent mixture of an alkanol containing from 2 to 5 carbon atoms per molecule and dimethyl formamide at a temperature below the boiling point of the solvent at contact conditions but above 70 F. so as to dissolve sulfonic acids in said solvent, the weight ratio of said alkanol to dimethyl formamide being in the range 1:4 to 4: 1; separatsolvents.

References Cited in the le of this patent UNITED STATES PATENTS Moran Feb. 21, 1928 6 Lazar et al. Oct. 15, 1940 Lohman et a1. June 17, 1941 Averill et al. Aug. 19, 1941 Showalter Jan. 21, 1947 OTHER REFERENCES Ward: Transactions Am. Inst. Chem. Engrs., vol. 38, pp. 931-46 (1942). 

1. THE PROCESS OF RECOVERING SULFONIC ACIDS FROM A PETROLEUM FRACTION CONTAINING SAID ACIDS, WHICH COMPRISES THE STEPS OF CONTACTING SAID PETROLEUM FRACTION WITH A SOLVENT MIXTURE OF AT LEAST ONE ALKANOL, SELECTED FROM THE GROUP CONSISTING C2 TO C5 ALKANOLS, AND DIMETHYL FORMAMIDE, THE RATIO OF SAID ALKANOL AND DIMETHYL FORMAMIDE BEING IN THE RANGE OF 1:4 TO 4:1, AT A TEMPERATURE BELOW THE BOILING POINT OF THE SOLVENT AT CONTACT CONDITIONS BUT ABOVE 70* F. SO AS TO SELECTIVELY DISSOLVE SAID ACIDS IN THE MIXTURE OF ALKANOL AND DIMETHYL FORMAMIDE; SEPARATING SAID SOLVENT AND ACIDS FROM SAID PETROLEUM FRACTION; AND SEPARATING SAID SULFONIC ACIDS AND SAID SOLVENT. 